Should I use kiln dried clear VG lumber?
This tutorial is aimed at giving the hollow wood board builder just enough information to make informed decisions at the lumberyard. If you are planning on building a guitar or fine furniture you should read a book on this subject.
Dryness
In order to build a light board you need dry wood. The less moisture trapped in the lumber when you glass your board the lighter it will be. There are three basic choices: Green, Kiln dried, or Air Dried.
Green Lumber
Green lumber is basically wood that is straight from the mill. It has average moisture content above 19 percent, making the lumber heavy and if stored outside they sometimes feel damp. As green lumber dries, it can shrink, warp and twist. Green lumber is usually less expensive than kiln-dried lumber and can be a wise choice if it is air-dried before use.
Kiln-Dried Lumber
Kiln dried lumber is green wood that has been put into a large oven and force dried down to approximately 12% moisture. The goal is to get the boards to dry quickly and evenly, and to prevent warping that could render the wood unusable.
Air-Dried Lumber
Sliver Paddleboards are made from air-dried lumber. Lumber is purchased well in advance and allowed to naturally lose moisture. Air-drying takes longer but since the moisture slowly comes out of the lumber, it causes no internal stress. (If the kiln schedule is correct, kiln dried lumber should also be free on internals stresses.) Sliver Paddleboards buys green lumber and lets it air dry in the shop after it has been reasawn into 1/4″ planks. The thin material thickness speeds up the drying process substantially.
Plain Sawn Lumber
Plain sawn
is the most common and widely used method of sawing lumber. Making the first cut on a tangent to the circumference of the log produces plain sawn lumber. Each additional cut is then made parallel to one before. This method produces the widest possible boards with the least amount of log waste. Therefore, it is more economical in comparison to the other sawing techniques utilized within the industry. The grain of plain sawn lumber has a distinct cathedral effect to on the face of some of the boards. Also commonly referred to as “flat sawn”. If you are buying Cedar from a local mill or lumber store, the wood will be plain sawn.
Quarter sawn lumber is the only other real choices since it would be nearly impossible to find Rift sawn cedar without buying the whole tree and having it milled. First quartering the log followed by sawing it perpendicular to the annual growth rings produces quarter-sawn lumber. This particular method of sawing produces a nice straight grain appearance on the face of the board. Quarter sawn lumber creates more log waste and therefore the end result is narrower boards in relation the plain sawn technique. If you are ordering your Cedar you might have this option but it is hard to find.
The best strategy in my opinion is to go shopping for lumber with the knowledge that Rift sawn or Quarter sawn lumber is ideally what you would like for it’s stability but plain sawn is usually all that is available. Although this seems like it would be a big problem it isn’t really. Every flat sawn log produces some lumber that has vertical grain lumber like rift sawn, and some close to vertical grain, like quarter-sawn lumber. Surf and paddleboards require such a small amount of boards it just requires some sorting through the pile to find the boards you want.
The pink rectangle is represents the butt end of a 2″ x 6″ taken from a Plain sawn from a log. The following statements are assuming that you will be resawing the boards into thin wide planks. The closer to VG grain the more dimensionally stable the piece of wood will be. Vertical grain is also easier to shape and sand as the summer and winter growth rings are of different hardness.
As you move closer to the top (pink rectangle) the grain will have a more cathedral pattern and the less stable the board will be. The more stable the grain (VG), the less interesting the grain pattern will be. As with all things in life, selecting lumber is a compromise.
All the boards between the two pink rectangles are decent choices.
Cupping, twisting, and warping will all become a greater risk with cathedral grain. The further away from vertical you are the more likely the wood will want to move. Tension is always released when you saw a board and the “funkier” the grain the more tension the board will have. When you look at the “butt” end of a board it is fairly easy to tell where in the log it came from. Have a look at all six sides before you choice the wood for your board.
Knots that run across the face should be avoided even if they are in the middle of the board you are buying. The paddle board pictured above had a hidden knot running across the face. Careful inspection would have showed the dime-sized knot. The two pieces that were usable had about 1 inch of unusable wood between them.
Quantity
You will need at least 3 true 2″ x 6″ boards to build a 30″ wide paddle board. It is nicer to have a little extra as not all wood is ascetically pleasing once it is book-matched. It is also nice to have some contrasting lumber for accents.
Summary
When you go to buy lumber for your board here are a few things to keep in mind.
- The nicer the wood you start with, the easier it is to build a nice looking board.
- Flat sawn lumber is less stable but looks great!
- Vertical edge grain boards are very stable.
- Boards that have minor flaws, small knots, are a little more work initially but have more visual interest.
- Knots running width-wise across the face of the lumber should be avoided.
- Buying “green” wood is fine since very thin boards dry very quickly.
